1. Field of the Invention
This invention relates to size compositions and more specifically it relates to polyvinyl alcohol based size compositions containing low ethylene oxide adduct additives.
2. Description of the Prior Art
Spun warp yarn must be sized with a water-soluble polymer which provides it with a protective surface coating the latter is required during the weaving of the yarn into fabric. After weaving the greige fabric produced must be stripped of the protective coating by desizing before it can be subjected to various finishing operations and in oarticular to dyeing. Sizes based on polyvinyl alcohol or combinations of polyvinyl alcohol and starch must generally be used with a wax additive present in the formulation to minimize drier drum sticking in the slasher during application of the size. These wax additives are difficult to remove from the greige fabric during desizing, often requiring extraction by special solvents as well as higher desize bath temperatures. As a consequence the finishing mill is faced with higher production costs due to greater process complexibility, higher energy costs and a higher percentage of second quality greige fabric.
The use of polyvinyl alcohol-based sizing solution containing a small amount of quaternary ammonium salt or a quaternary imidazolinium salt is disclosed in U.S. Pat. No. 4,383,063; these additives provide good operability in the absence of wax and result in fabric exhibiting improved finishing performance. However, such formulations have the serious deficiency of frequently exhibiting a non-reproducible sizing performance; the latter is due to an erratic and unpredictable removal of the cationic additive by inter-action with anionic contaminants which tend to accumulate in the sizing solution. The primary source of these anionic contaminants is the spun varn being sized.
The incorporation into polyvinyl alcohol-based sizes of very low levels (maximum of 0.05 wt. % based on polvvinyl alcohol) of low ethoxylate adducts of linear alcohols as defoaming agents is disclosed in U.S. Pat. No. 4,251,403; such materials have been found to be ineffective as wax substitutes and therefore are not used as substitutes for wax in wax-free warp sizing compositions.